The present invention relates to a computer-implemented method of and system for teaching an untrained observer to evaluate a gemstone such as a cut diamond. In particular, but not exclusively, the present invention relates to a computer-implemented method of and system for teaching an untrained observer to appreciate the effect of cut on the value of a gemstone, and to provide the untrained observer with an opportunity to evaluate and compare gemstones for himself or herself.
The beauty of a gemstone, such as a cut diamond, derives from its light handling ability. What attracts the eye is the xe2x80x9cgame of lightxe2x80x9d played by a well-cut diamond as incident light is reflected and refracted off its many facets. Diamonds and other gemstones have been cut, polished and worn as jewelry for thousands of years. They may be cut according to many different cut patterns such as the round brilliant, oval, pear, marquise, radiant, princess, heart, emerald cut etc. The most popular cut today is known as the standard round brilliant (SRB) cut as shown in FIGS. 1a and 1b. 
The precursor to the modern SRB cut emerged in 1919 with Marcel Tolkowsky""s seminal work entitled, xe2x80x9cDiamond Design: A Study of the Reflection and Refraction of Light in Diamond.xe2x80x9d This work marked a breakthrough in the theoretical understanding of how cut affects light handling ability. Tolkowsky suggested certain cut proportions (i.e., the geometry) of a round brilliant diamond which should produce near optimal light performance. Today, research into the cut of a diamond is greatly advanced and techniques are being used, such as computer modeling, to study the complex optics of the SRB cut. However, the modern SRB cut bears much similarity with the round brilliant cut originally proposed by Tolkowsky.
When purchasing a gemstone, such as a cut diamond, an untrained observer typically relies on the skill and knowledge of the jeweler to explain the differences between one gemstone and another. When describing a cut diamond to an untrained observer, the jeweler may refer to what are known as the four C""sxe2x80x94its carat weight, clarity, color, and cut. Each of these factors has an effect on the value of the diamond. Of these factors, the effect of carat weight is relatively straightforward for the untrained observer to understandxe2x80x94the value of a cut diamond generally increases with increasing carat weight. Similarly, the effects of clarity (clear diamonds are generally more valuable than less clear diamonds) and color (colorless diamonds are generally more valuable than colored diamonds) are relatively straightforward for the untrained observer to understand.
However, it is the cut of a diamond, and its dramatic effect on light handling ability, that has the most significant effect on value. Diamond cutting and polishing is a highly skilled art and a well-cut diamond will command a significant price premium over an otherwise identical but poorly cut diamond. In the words of one expert xe2x80x9ccut is king!xe2x80x9d However, given the theoretical complexity of the effect of cut on the optical performance of a gemstone, it is hardly surprising that it is the most difficult factor for a jeweler to explain to an untrained observer.
When describing the light handling abilities of cut gemstones, gemologists sometimes refer to optical properties of gemstones such as brilliance (the intensity of light returned), scintillation (fast and local fluctuations in the light returned as the gemstone moves relative to the lighting conditions), fire (the dispersion of white light into spectral colors as it refracts off the facets of the gemstone) and symmetry (the symmetry of light patterns such as the so-called xe2x80x9chearts and arrowsxe2x80x9d visible from the pavilion and table sides of an SRB cut diamond). However, analysis of gemstones according to these optical properties has mostly been a subjective exercise undertaken only by trained gemologists with substantial experience of examining gemstones. Untrained observers do not have the knowledge or experience to judge these optical properties for themselves. A potential purchaser, when shown a particular cut diamond under the controlled lighting conditions of a jeweler""s shop, may like it or dislike it. Furthermore, he or she may subjectively prefer one diamond to another. But without training and experience, he or she will not be able to judge the light handling performance of a diamond at a level sufficient to explain the significant price premium which a well-cut diamond will command over an otherwise identical but poorly cut diamond.
Recently, electronic gemstone analyzing systems have become available which measurements of optical properties of gemstones to be taken. International Patent Publication number WO 96/23207 describes a device which captures color images of a gemstone placed in an analysis chamber and illuminated by a uniform annular light which may be moved along an axis such that the gemstone may be illuminated from a plurality of different angles. The device performs a spectral analysis of the captured images using a tunable optical band pass filter to determine the color of the gemstone. Digital images of the gemstone may also be stored, displayed or transmitted over a data network.
The website (www.gemex.com) of GemEx Systems, Inc, a US company, describes a device called the BrillianceScope Analyzer which is described as an imaging spectrophotometer. Color images of a diamond are captured in a controlled lighting environment consisting of six lighting angles, five of which provide reflected light and one of which provides diffuse lighting. These images may then be analyzed to generate a report on the diamond. The BrillianceScope Analyzer device operates on the same principle as the device described in International Patent Publication number WO 96/23207 referred to above, in that the gemstone is placed in an analysis chamber and illuminated by a uniform annular light which may be moved along an axis such that the gemstone is illuminated from different angles. The images may be analyzed by a computer, and the properties of xe2x80x9cwhite lightxe2x80x9d, xe2x80x9ccolored lightxe2x80x9d and xe2x80x9cscintillationxe2x80x9d for a diamond are determined and displayed on three line chart scales from xe2x80x98lowxe2x80x99, to xe2x80x98mediumxe2x80x99 to xe2x80x98highxe2x80x99. Captured images may also be shown in a repeating sequence in one display area, giving the effect of light movement.
International Patent Publication number WO 99/61890 describes a system for the standardized grading of gemstones. A gemstone is subject to a plurality of incident light sources and images are captured for analysis. Images of the gemstone, such as a SRB cut diamond, may be captured from various viewpoints such as from the pavilion, from the crown and side-on. The gemstone is supported by a rotatable platform which is rotated when images are being captured from a side-on viewpoint to obtain profile and color images from a variety of rotational positions and to detect internal flaws and inclusions. When capturing images from above and below the gemstone, the platform is moved along an axis from a level position to a down and an up position respectively. The fixed focal length camera is also moved along an axis to focus on the gemstone when the platform is moved between the up, down and level positions. A captured image may be analyzed by a processor to obtain color measurements and measures of the brilliance and scintillation of the gemstone.
The above-described electronic gemstone analyzing systems are suited for use by trained professionals, such as gemologists or jewelers. None of the systems provides teaching enabling an untrained observer, such as a potential purchaser of a cut diamond, to understand the significance of the results of analysis.
Accordingly, certain inventive aspects relate to a system, method and computer program for teaching an untrained observer to evaluate a gemstone for himself or herself.
More particularly, one inventive aspect enables the untrained observer to understand the effect of cut on light handling ability to a sufficient level to be able to appreciate its significant effect on the value of a gemstone.
Furthermore, another inventive aspect enables the untrained observer to measure optical properties of particular gemstones and thereby judge the light handling ability of a gemstone for himself or herself.
Another aspect is to provide a system, method and computer program for enabling an untrained observer to evaluate cut gemstones which is more compact, lightweight, mechanically simpler, and therefore less expensive to manufacture, than conventional apparatus, making it more suitable for use in retail premises, such as jeweler""s shops.
Yet another aspect is to provide a potential purchaser of a gemstone with an improved retail experience, thereby increasing sales.
According to one embodiment a computer-implemented method is provided that teaches a user to evaluate a gemstone, such as a cut diamond. The method includes providing a computer system connected to an apparatus capable of capturing an image of a gemstone. The computer system is arranged to process a received image of a gemstone to determine one or more optical properties of the gemstone. The method presents on a display of the computer system a series of pre-stored screens comprising a graphical representation how the cut of a gemstone affects its light handling ability, and a user interface screen. The user interface screen allows the user to control the operation of the apparatus to measure the one or more optical properties of a particular gemstone provided to the apparatus, to view an image of the gemstone measured, and to view representations of the measured one or more optical properties.
As discussed above, the effect of cut on light handling ability and thus on the value of a diamond is dramatic. However, given the theoretical complexity of the relationship between cut and optical performance, it is hardly surprising that it is the most difficult factor for a jeweler to explain to a potential purchaser of a diamond who is most likely to be untrained and inexperienced in gemology. The potential purchaser, when shown a particular cut diamond under the controlled lighting conditions of a jeweler""s shop, may like it or dislike it. Furthermore, he or she may subjectively prefer one diamond to another. But, when purchasing a cut diamond, often for tens of thousands of dollars, he or she would clearly benefit from the opportunity to make a better informed purchasing decision for himself or herself. The present invention provides the potential purchaser with a deeper understanding of how cut effects light handling ability and thus how it effects the value of a gemstone. Furthermore, the present invention provides the potential purchaser with the ability to analyze gemstones in terms of measurable optical properties and thus to determine, for himself or herself, objective differences in the light handling abilities of particular cut gemstones. A deeper theoretical understanding of the effect of cut, together with the means to evaluate the light handling ability of particular cut gemstones provides the potential purchaser with the information needed to make a well-informed purchasing decision. Overall, the present invention provides a better retail experience to the potential purchaser of a gemstone, such as a cut diamond, thereby increasing customer satisfaction and sales alike.
In certain embodiments, the graphical representation of how the cut of a gemstone affects its light handling ability comprises a moving image of how incident light reflects or refracts off the facets of a cut gemstone. A graphical moving image is ideal for helping the untrained observer to understand how cut effects light handling ability.
In certain embodiments, the graphical representation of how the cut of a gemstone affects its light handling ability comprises a moving image of how incident light reflects or refracts off the facets of both an ideal cut gemstone and a non-ideal cut gemstone, whether shallow cut or deep cut. Thus, the untrained observer can visualize how the light handling ability of an ideal cut is superior to that of either a shallow or deep cut.
In certain embodiments, the series of pre-stored screens comprises a description of how the carat weight of a gemstone cut from a rough stone depends on whether the cut is ideal or non-ideal, whether shallow cut or deep cut. Thus, the untrained observer can see how obtaining the maximum carat weight from an uncut rough stone will in general be at the expense of obtaining an ideal cut, and, vice verse, how obtaining an ideal cut will in general be at the expense of obtaining the maximum carat weight from an uncut rough stone. Thus, the untrained observer will appreciate how cut may be more significant than carat weight in its effect on value.
In certain embodiments, the series of screens comprises a graphical representation of the light handling phenomenon of the SRB cut known as xe2x80x98hearts and arrowsxe2x80x99. Thus, the untrained observer is shown how a perfectly-cut SRB gemstone produces a highly symmetrical pattern of light and dark regions forming the xe2x80x98hearts and arrowsxe2x80x99 and is better able to compare images of a particular gemstone against how a perfectly cut SRB gemstone would look.
In certain embodiments, the apparatus is arranged to illuminate the gemstone with a spatially varied light pattern and to capture images of the gemstone at each of a plurality of rotational positions of the light pattern relative to the gemstone, the one or more optical properties being determined in dependence on each of these images. Thus, the one or more optical properties are determined from images of the gemstone illuminated under lighting conditions that correspond to normal lighting conditions of gemstones worn in jewelry.
In certain embodiments, the light pattern is selected in dependence on a cut pattern of a standardized gemstone cut. Thus, the one or more optical properties are more accurately measured for the particular gemstone measured.
In certain embodiments, the user may view images of and representations of one or more optical properties in respect of two gemstone measured on a single screen. Thus, the user may more easily compare the light handling abilities of two particular gemstones.
In certain embodiments, the method further presents on the display of the computer system a user interface screen whereby a user may retrieve and display pre-generated reports on gemstones.
Thus, the user may use previously generated reports of gemstones for comparison or for information.
In certain embodiments, the pre-generated reports on gemstones are stored remotely to the computer system and are retrieved over a telecommunications link. Thus, the gemstone reports may be maintained and updated centrally and accessed by several different users perhaps in different jeweler""s shops.